Dynamic simulation of void nucleation during electromigration in narrow integrated circuit interconnects

Electromigration (EM) is an important failure mechanism in integrated circuit interconnections. Various models have been proposed to study the interconnect degradation due to EM from different perspectives. As the interconnect linewidth shrinks to submicrometer and below, a small growth in void size after void nucleation can sever the conduction path, and hence void nucleation time becomes the dominant part of the time to failure of an interconnect and the primary damage mechanism in EM failure. In this work, an alternative concept of EM modeling is proposed, and the EM lifetime of an interconnect during void nucleation is derived theoretically. A physics-based predictive Monte Carlo simulation methodology is used to model the void nucleation process during EM. To demonstrate the modeling concept and the simulation methodology developed in the present study, Al interconnect test structure is chosen as an illustration and it is shown that the model can predict the voiding location in the interconnect and estimate the median time to failure as verified experimentally.